UVPES and ab initio molecular orbital studies on the electron donor-acceptor complexes of bromine with methylamines

The He I photoelectron spectra of bromine, methylamine, and their complex have been obtained, and the spectra show that lone-pair orbital energy of nitrogen in methylamine is stabilized by 1.8 eV and the bromine orbital energies are destabilized by about 0.5 eV due to complexation. Ab initio calculations have been performed on the charge-transfer complexes of Br-2 with ammonia and methyl-, dimethyl-, and trimethylamines at the 3-21G*, 6-311G, and 6-311G* levels and also with effective core potentials. Calculations predict donor and acceptor orbital energy shifts upon complexation, and there is a reasonable agreement between the calculated and experimental results. Complexation energies have been corrected for BSSE. Frequency analysis has confirmed that ammonia and trimethylamine form complexes with C-3v symmetry and methylamine and dimethylamine with C-s symmetry. Calculations reveal that the lone-pair orbital of nitrogen in amine and the sigma* orbital of Br-2 are involved in the charge-transfer interaction. LANL1DZ basis seems to be consistent and give a reliable estimate of the complexation energy. The computed complexation energies, orbital energy shifts, and natural bond orbital analysis show that the strength of the complex gradually increases from ammonia to trimethylamine.

Robust Relay Precoder Design for MIMO-Relay Networks

In this paper, we consider a robust design of MIMO-relay precoder and receive filter for the destination nodes in a non-regenerative multiple-input multiple-output (MIMO) relay network. The network consists of multiple source-destination node pairs assisted by a single MIMO-relay node. The source and destination nodes are single antenna nodes, whereas the MIMO-relay node has multiple transmit and multiple receive antennas. The channel state information (CSI) available at the MIMO-relay node for precoding purpose is assumed to be imperfect. We assume that the norms of errors in CSI are upper-bounded, and the MIMO-relay node knows these bounds. We consider the robust design of the MIMO-relay precoder and receive filter based on the minimization of the total MIMO-relay transmit power with constraints on the mean square error (MSE) at the destination nodes. We show that this design problem can be solved by solving an alternating sequence of minimization and worst-case analysis problems. The minimization problem is formulated as a convex optimization problem that can be solved efficiently using interior-point methods. The worst-case analysis problem can be solved analytically using an approximation for the MSEs at the destination nodes. We demonstrate the robust performance of the proposed design through simulations.

Alternating current conduction behavior of excimer laser ablated SrBi2Nb2O9 thin films

Bi-layered Aurivillius compounds prove to be efficient candidates of nonvolatile memories. SrBi2Nb2O9 thin films were deposited by excimer laser ablation at low substrate temperature (400 °C) followed by an ex situ annealing at 750 °C. The polarization hysteresis behavior was confirmed by variation of polarization with the external applied electric field and also verified with capacitance versus voltage characteristics. The measured values of spontaneous and remnant polarizations were, respectively, 9 and 6 μC/cm2 with a coercive field of 90 kV/cm. The measured dielectric constant and dissipation factors at 100 kHz were 220 and 0.02, respectively. The frequency analysis of dielectric and ac conduction properties showed a distribution of relaxation times due to the presence of multiple grain boundaries in the films. The values of activation energies from the dissipation factor and grain interior resistance were found to be 0.9 and 1.3 eV, respectively. The deviation in these values was attributed to the energetic conditions of the grain boundaries and bulk grains. The macroscopic relaxation phenomenon is controlled by the higher resistive component in a film, such as grain boundaries at lower temperatures, which was highlighted in the present article in close relation to interior grain relaxation and conduction properties.

Auditory-motivated Gammatone wavelet transform

The ability of the continuous wavelet transform (CWT) to provide good time and frequency localization has made it a popular tool in time-frequency analysis of signals. Wavelets exhibit constant-Q property, which is also possessed by the basilar membrane filters in the peripheral auditory system. The basilar membrane filters or auditory filters are often modeled by a Gammatone function, which provides a good approximation to experimentally determined responses. The filterbank derived from these filters is referred to as a Gammatone filterbank. In general, wavelet analysis can be likened to a filterbank analysis and hence the interesting link between standard wavelet analysis and Gammatone filterbank. However, the Gammatone function does not exactly qualify as a wavelet because its time average is not zero. We show how bona fide wavelets can be constructed out of Gammatone functions. We analyze properties such as admissibility, time-bandwidth product, vanishing moments, which are particularly relevant in the context of wavelets. We also show how the proposed auditory wavelets are produced as the impulse response of a linear, shift-invariant system governed by a linear differential equation with constant coefficients. We propose analog circuit implementations of the proposed CWT. We also show how the Gammatone-derived wavelets can be used for singularity detection and time-frequency analysis of transient signals. (C) 2013 Elsevier B.V. All rights reserved.

Regionalization of extreme rainfall in India

Regionalization of extreme rainfall is useful for various applications in hydro-meteorology. There is dearth of regionalization studies on extreme rainfall in India. In this perspective, a set of 25 regions that are homogeneous in 1-, 2-, 3-, 4- and 5-day extreme rainfall is delineated based on seasonality measure of extreme rainfall and location indicators (latitude, longitude and altitude) by using global fuzzy c-means (GFCM) cluster analysis. The regions are validated for homogeneity in L-moment framework. One of the applications of the regions is in arriving at quantile estimates of extreme rainfall at sparsely gauged/ungauged locations using options such as regional frequency analysis (RFA). The RFA involves use of rainfall-related information from gauged sites in a region as the basis to estimate quantiles of extreme rainfall for target locations that resemble the region in terms of rainfall characteristics. A procedure for RFA based on GFCM-delineated regions is presented and its effectiveness is evaluated by leave-one-out cross validation. Error in quantile estimates for ungauged sites is compared with that resulting from the use of region-of-influence (ROI) approach that forms site-specific regions exclusively for quantile estimation. Results indicate that error in quantile estimates based on GFCM regions and ROI are fairly close, and neither of them is consistent in yielding the least error over all the sites. The cluster analysis approach was effective in reducing the number of regions to be delineated for RFA.

Electron quantum path tuning and isolated attosecond pulse emission driven by a waveform-controlled multi-cycle laser field

We investigate high-order harmonic emission and isolated attosecond pulse (IAP) generation in atoms driven by a two-colour multi-cycle laser field consisting of an 800 nm pulse and an infrared laser pulse at an arbitrary wavelength. With moderate laser intensity, an IAP of similar to 220 as can be generated in helium atoms by using two-colour laser pulses of 35 fs/800 nm and 46 fs/1150 nm. The discussion based on the three-step semiclassical model, and time-frequency analysis shows a clear picture of the high-order harmonic generation in the waveform-controlled laser field which is of benefit to the generation of XUV IAP and attosecond electron pulses. When the propagation effect is included, the duration of the IAP can be shorter than 200 as, when the driving laser pulses are focused 1 mm before the gas medium with a length between 1.5 mm and 2 mm.

El discurso en el estudio de las organizaciones. Una revisión de la literatura

[ES] En el documento se presenta una revisión de la literatura referente al discurso en el estudio de las organizaciones, que parte de sus fundamentos teóricos y sus principales aportes. La unidad de análisis fueron 88 textos seleccionados en una revisión sistemática de 5.509 artículos, publicados entre 2000 y 2012, en diez de las principales revistas internacionales relacionadas con la temática definida. Para relevar y categorizar los datos pertinentes, se utilizó el software de investigación cualitativa Atlas.ti, versión 6.2. La comprensión de la información se complementó con métodos de análisis de contenido y de frecuencia. De los principales resultados se infirieron cuatro dimensiones del discurso: instrumental, simbólica, estratégica y comunicacional. Además, se realizó una clasificación de los artículos con base en los enfoques sobre el discurso y las temáticas organizacionales estudiadas. Los aportes encontrados en dicha revisión permiten plantear que el discurso no solo es lo dicho sino también aquello que ha sido silenciado en la organización, campo de investigación que ha sido poco explorado en los textos analizados. Este artículo realiza contribuciones importantes para el área administrativa y organizacional, en especial para todos aquellos profesionales que se interesen por el análisis de las organizaciones desde la perspectiva del discurso, tanto en la academia como en la asesoría e intervención en ellas.

Population parameters of Penaeus californiensis in the Gulf of Guayaquil, Ecuador

The growth, mortality, and recruitment pattern of Penaeus californiensis were investigated using tail length (TL)-frequency data obtained from the Gulf of Guayaquil shrimp population. Computer-based methods of tail-frequency analysis Compleat ELEFAN software were used. Results obtained gave relatively high growth and mortality estimates for both males and females. The recruitment pattern indicated two pulses annually, one significantly larger than the other.

Growth and mortality of dagaa (Rastrineobola argentea, Fam. Cyprinidae) in Lake Victoria

Growth and mortality parameters of the small Lake Victoria cyprinid Rastrineobola argentea were determined from length-frequency analysis, using the ELEFAN I and II programs. The results of two sampling programs, both performed during 1988, one in Uganda (mosquito seine) and the other in Tanzania (pelagic trawl), were highly corresponding, In comparison with previously published data on the growth of dagaa and some similar species, low values for L sub( infinity ) (65 mm standard length) and K (1 year super(-1)) were found. Total mortality (Z) amounted to 3.9-4.4 year super(-1). A single annual breeding peak was observed both in Uganda (October/November) and in Tanzania (February/March).

Análise de critérios para definição da vazão remanescente em usinas hidrelétricas.

Tem crescido a demanda por energia em todo o mundo. No Brasil, com o aquecimento da economia aumentam ainda mais as pressões. O parque gerador Brasileiro é fortemente baseado na geração hidrelétrica, que representa aproximadamente 77,6% da oferta de geração de eletricidade. Entre os impactos ambientais gerados pela construção de barragens e reservatórios de aproveitamentos hidrelétricos está a mudança do regime fluvial de jusante, a chamada vazão remanescente. Entre outros, esta vazão deve garantir as condições adequadas à sobrevivência e continuação das espécies e dos ecossistemas, associando as necessidades humanas, ambientais e as características de cada região. Tomou-se como objeto de análise dois estudos de caso, a pequena central hidrelétrica (PCH) Santa Gabriela, localizada no rio Correntes, na divisa entre os estados de Mato Grosso e Mato Grosso do Sul e a usina hidrelétrica (UHE) Batalha, situada no rio São Marcos, na divisa entre os estados de Minas Gerais e Goiás. Embora o assunto seja discutido amplamente pela comunidade técnica e acadêmica, não há ainda nos marcos legais Brasileiros associados, uma definição explícita de critérios ou limites para estabelecimento da vazão remanescente. Em geral, as legislações estaduais estabelecem valores máximos outorgáveis determinados a partir de percentuais da curva de permanência (Q90, Q95) ou da vazão mínima anual de sete dias de duração e tempo de recorrência de 10 anos Q7,10, garantindo consequentemente as vazões mínimas remanescentes. Essas metodologias implicam num único valor fixo para a vazão ao longo do ano, o que não condiz com a realidade do regime hidrológico natural. Estudos atuais apontam para um hidrograma ecológico, que represente a variação das vazões entre os meses de estiagem e cheia. Assim, a metodologia envolveu a comparação entre critérios de outorga utilizados em alguns estados Q90, Q95 e Q7,10 e métodos citados na literatura para estudo da vazão ecológica (Tennant, Texas, Vazão Base e Perímetro Molhado) e as Resoluções referentes à Declaração de Reserva de Disponibilidade Hídrica (DRDH) das usinas, que especificam a vazão remanescente nas fases de enchimento e operação, emitidas pela Agência Nacional de Águas (ANA). Observaram-se valores de vazões substancialmente diferenciados entre os seis métodos empregados. Cabe destacar, que representa um avanço a publicação do Manual de Estudos de Disponibilidade Hídrica para Aproveitamentos Hidrelétricos (ANA, 2009), que visa à padronização dos documentos para fins obtenção da DRDH e da outorga do uso do potencial de energia hidráulica em corpo de água de domínio da União. Assim, o empreendedor poderá propor e negociar a demanda hídrica para as necessidades ambientais com as autoridades competentes, o que deverá ser discutido em reunião técnica inicial que deverá contar com a participação da Agência Nacional de Energia Elétrica (ANEEL), ANA, órgão ambiental, empreendedor e a empresa responsável pelos estudos ambientais.

Age determination and growth of the night shark (Carcharhinus signatus) off the northeastern Brazilian coast

Age and growth of the night shark (Carcharhinus signatus) from areas off northeastern Brazil were determined from 317 unstained vertebral sections of 182 males (113–215 cm total length [TL]), 132 females (111.5–234.9 cm) and three individuals of unknown sex (169–242 cm). Although marginal increment (MI) analysis suggests that band formation occurs in the third and fourth trimesters in juveniles, it was inconclusive for adults. Thus, it was assumed that one band is formed annually. Births that occur over a protracted period may be the most important source of bias in MI analysis. An estimated average percent error of 2.4% was found in readings for individuals between two and seventeen years. The von Bertalanffy growth function (VBGF) showed no significant differences between sexes, and the model derived from back-calculated mean length at age best represented growth for the species (L∞=270 cm, K=0.11/yr, t0=–2.71 yr) when compared to the observed mean lengths at age and the Fabens’ method. Length-frequency analysis on 1055 specimens (93–260 cm) was used to verify age determination. Back-calculated size at birth was 66.8 cm and maturity was reached at 180–190 cm (age 8) for males and 200–205 cm (age ten) for females. Age composition, estimated from an age-length key, indicated that juveniles predominate in commercial catches, representing 74.3% of the catch. A growth rate of 25.4 cm/yr was estimated from birth to the first band (i.e. juveniles grow 38% of their birth length during the first year), and a growth rate of 8.55 cm/yr was estimated for eight- to ten-year-old adults.

Stock assessment of soldier catfish Osteogeneiosus militaris along the northwest coast of India

Value of length growth parameters L∞, K and t(sub)0 from age-length relation obtained from length-frequency analysis for the soldier catfish stock were estimated to be 47.6 cm, 0.51 per year and 0.03 year respectively. The age at recruitment (t [sub]r) was 0.58 year and the age at first capture (t[sub]c) 0.83 year. The total mortality (Z) was 0.88 including the present natural mortality (M) of 0.84 and fishing mortality (F) of 0.04. The total stock of this fish along the Northwest coast of India was assessed to be 32,413 tons and the MSY 5,426 tons which is much higher than the current catch of 863.8 tons. The potential yield (P[sub]y) of 38.7 g per recruit could be obtained at the optimum of exploitation (t[sub]y) of 2.84 years.

Reproduction, age and growth of the kelee shad, Hilsa kelee (Cuvier, 1829) (pisces: fam. Clupeidae) with informations on its fishery in Maputo Bay, Mozambique

Age, growth and reproduction of H. kelee were studied, and a brief description of its fishery in Maputo Bay (Mozambique) is given. Most material was collected from gill net fisheries during 1977-1980, but some was taken from shrimp trawlers operating in the same area during 1980-1981. Main spawning takes place during October-January with a peak in December. There is also some evidence that spawning takes place during June-July. The size at first maturity was approximately equals 14-15 cm. Ageing was carried out using primary growth rings in the otoliths and length-frequency analysis of fish caught by shrimp trawlers. Von Bertalanffy's growth equation parameters were determined. Males and females grew in similar fashion. There are seasonal trends in the catch composition of the gill net fishery, showing high values during April to September and low during October to December.

Population dynamics and stock assessment of the common carp (Cyprinus carpio) in Iranian waters of the Caspian Sea

In order to come up with the responsible fishing pattern of common carp, there was a need to identify some of the biological characteristics and stock assessment of carp in Iranian waters of the Caspian Sea .The fork length ,weight ,age ,growth parameters of von bertalanffy and mortality rates of common carp were estimated from oct 2006 to sept 2007.Based on the exponential relationship between length and weight in the size range 6.3-65.6 cm ,b was calculated 2.895, 2.843 and 2.925 respectively for combined sexes ,males and females. The mean condition factor was 1.9 which is close to the ideal condition.The results from measuring 3170 specimens ,were showed the first fork length of maturity was 30 cm for males and 32 cm for females. The results indicated that females were predominate and sex ratio was 0.66:1 (M:F) and chi-squares analysis showeda significant difference between males and females.(p<0.05).Length infinity and growth coefficient were calculated by three different methods as below: Length frequency analysis : k=0.17 L∞ =68.04 Age-Length Key k=0.15 L∞ =74.25 Back calculation : k=0.14 L∞ =68.4 The mortality parameters and exploitation rate were estimated as below : Z=0.73 per year M=0.31 per year F=0.42 per year E=0.56 Refer to amount of common carp catch in 2007 -08 ,biomass was calculated 9640.2 tones by jone's cohort analysis and MSY 2374.5 tones.According to analysis ,the number of common carp in the distribution area (Iranian part of the Caspian Sea ) was estimated 24 millions in the 2006-07.

Biology of the penaeid shrimp populations exploited by Estuarine Set Bagnet

Results of analysis of part of the data collected during October, 1989 to December, 1990 are given on the biology and catch assessment studies on the Estuarine Set Bagnet (ESBN) from six sampling stations covering the entire coast line of Bangladesh. Length frequency analysis of seven most commonly occurring penaeid shrimp species have been done with complete ELEFAN software package. The result of exploitation patterns indicate that all penaeids except P. stylifera are being over exploited on their way back to the Sea from the nursery ground. This appeared to be the instances of serious growth over fishing. These species are exploited at a size much lower than the length at first maturity, which strongly suggests a complete withdrawal of the bagnet fishery from the coast of Bangladesh.